18 BRITISH OOLITIC AND LIASIC BRACHIOPODA. 



The larger valve only of this small species is known ; from which it appears, that it 

 differed materially from L. Moorei, being much more convex, and the striae ornamenting 

 its surface having two or three smaller intermediate ones (Plate I, fig. 19*5); while in 

 L. Moorei the costae appear of the same size ; the shape of this shell is also more rounded, 

 and considerably larger than L. Moorei. Length 3^ ; breadth 4^ lines. 



This species appears to be rare ; it occurs in a clay stratum above the Leptaena bed : 

 it was discovered by Mr. Moore. 



Plate I, fig. 19, nat. size; fig. 19a, b, enlarged. 



14. Lept.<ena granulosa, Dav. Plate I, fig. 20. 



Leptaena granulosa, Dav. Bull. Soc. Geol. de France, vol. vi, 2 de Serie, p. 270, 

 fig. 6, 1850. 



Diagnosis. Valve slightly convex, rounded and ornamented by granulous striae, 

 between which smaller ones are perceived (Plate I, fig. 203); the area appears narrow, 

 and has much resemblance to L. Moorei. Length 1^; breadth 2 lines. 



It is a rare species ; easily distinguished from L. Pearcei and L. Moorei by the 

 granulations which ornament its valves : it was found by Mr. Moore in the upper Lias, 

 in the same bed which contains L. Pearcei. Only the larger valve is known, and therefore 

 it can be but imperfectly described. 



Plate I, fig. 20, natural size. 

 „ fig. 20a, b, enlarged. 



15. Lepttena liasiana, Bouchard. Plate I, fig. 21. 



Lept^na liasiana, Bouchard. 1847. Annals and Mag. of Nat. Hist., t. 18, fig. 2, a — d. 



— — Dav. 1850. Bull. Soc. Geol. de France, vol, vi, 2 ie Serie, p. 270. 



— — DOrb. Prodrome, vol. i, p. 220. 



Diagnosis. " Shell rounded, inequivalved, equilateral, smooth ; larger valve gibbose pos- 

 teriorly, becoming flatter anteriorly, with a slight longitudinal groove ending in a notch on 

 the front margin of the shell. Beak small, slightly incurved, truncated at the apex by a 

 minute circular foramen, similar to that which occurs in many other Leptanas; for instance, 

 L. altemata, of Indiana, North America. This truncation may also be observed in some 

 species of Orthis, from Russia. Area double, interrupted on the dorsal valve by a large 

 and slightly-convex deltidium, which arises at the apical opening, and gradually enlarges 

 towards the base, occupying one third of the width of the area. The deltidium is slightly 

 notched, the notch being partly closed by the large median tooth of the smaller valve ; the 

 exterior face of which is grooved by four furrows, which afforded a passage for the muscular- 

 fibres of attachment, arranged in four bundles. The smaller valve is deeply concave, fol- 



